Soil compaction machine



Jan. 29, 1963 J. MGRAE soIL coMPAcTIoN MACHINE 8 Sheets-Sheet 1 Filed May 6, 1960 INVENTOR. /I//Flj dO//V Jan. 29, 1963 J. L. MGRAE son. coMPAcTIoN MACHINE 8 Sheets-Sheet 2 Filed May e, 1960 Jan. 29, 1963 J. L. MCRAE SOIL COMPACTION MACHINE Filed May .6. 1960 FVG. S.

8 Sheets-Sheet 3 INVENTOR.

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Jan. 29, 1963 J. l.. MCRAE 3,075,436

SOIL COMPACTION MACHINE Filed May 6, 1960 8 Sheets-Sheet 4 FIG. .10.

Jan. 29, 1963 J. L. MCRAE son. coMPAcTIoN MACHINE 8 Sheets-Sheet 5 Filed May 6. 1960 IN1/Emol;

SQ l I i I m58! .N|N.. .muu

Jan. 29, 1963 J'. L. MCRAE 3,075,436

' soIL coMPAcTIoN MACHINE Filed May e, 1960 8 sheets-sheet 6 INVEN TOR.

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Jan. 29, 1963 J. L. MGRAE soIL coMPAcTIoN MACHINE 8 Sheets-Sheet '7 Filed May e, 19Go INlf/,ENTOIL l daf/Af L. ice/7E,

J. L. MCRAE SOIL COMPACTION MACHINE Jan. 29, 1963 8 Sheets-Sheet 8 Filed May 6', 1960 FVG. 15.

I NV EN TOR, M .c 45

27X mmf/ 3,075,436 SOIL `C(Bll/ilPAC'fIlsI MACHINE Kohn L. McRae, Vicksburg, Miss., assignor to Engineering Developments Co., Inc., Vicksburg, Miss. Filed May 6, 1960, Ser. No. 27,394 6 Ciams. (Cl. 94-4%) The present invention relates to a machine for compacting or tamping soils to develop a solid earth surface for a base for roads, airstrips, construction sites, or the like.

In the preparation of a base for a road, airport strip, or other area in which it is desirable to have a dense soil base, it is extremely important that the layers of soil be uniform by compacting in the bottom layer to the top layer. Previously proposed and presently in use are soil compacting machines of Various types. Rollers have been employed and vibrators have been employed either singly or in conjunction with a roller but the same have not `been entirely successful for many reasons. A chief defect is that the rollers apply a squeezing action which did not overcome the friction between the particles of the -soils being compacted and the vibrator is then employed and serves to partially overcome the friction of the soil particles so that the particles move with respect to each other and develop a more compact mass and reduce by the squeezing action of the rollers.

A primary object of the present invention is to provide a soil compaction machine having tamping shoes arranged in tandem relation so that when the machine is driven over a ground surface, the tamping shoes penetrate a layer of uncompacted soil and provide, as the machine is moved, a completely compacted surface which is of uniform density from the bottom of the soil layer to the top of the layer.

Another object of the present invention is to provide a soil compaction machine which lends itself to compacting a soil layer at a single pass.

A further object of the present invention is to provide a soil compaction machine having tamping shoes which serve to strike or tamp soil on a ground surface, the tamping shoes and mechanisms operating the same and eing arranged so that they may be driven in unison, alternatingly, in pairs, or individually as desired.

A still further object of the present invention is to provide a soil compaction machine having a plurality of tamping shoes independently suspended so that they adjust themselves to uneven ground surfaces with ease and facility.

Yet another object of the invention is to provide a soil compaction machine having a plurality of impact tamping units in which the sequence of the units may be varied so that the units strike the ground in any sequence desired, this being accomplished by varying the relative position of the eccentric weights of the units and permitting adjustment in total impact load against the earth for each downward stroke and also adjustment in the frequency with which the earth is struck while maintaining a given relatively low-frequency, high-arnplitude motion for cach individual oscillator mechanism, thus producing high frequency vibration in the earth by means of a series of low frequency impact tampers. This results in the larger mass of the earth being consolidated by high frequency impulses while the localized mass at the 'surface is being compacted by the sharp penetrating blows of the individual impact shoes.

These and other objects and advantages of the present invention will be fully apparent from the following description when taken in conjunction with the annexed drawings, in which:

FIGURE 1 is a top plan view of the soil compaction machine according to the present invention;

'sn-reinas Patented Jan. 29, i963 FIGURE 2 is a side elevational view of the assembly shown in FIGURE 1;

FIGURE 3 is a view on an enlarged scale, taken on the line 3 3 of FIGURE 2;

FIGURE 4 is aysectional View of one of the units of the assembly of FIGURE 3;

FIGURE 5 is a View taken on the line 5 5 of FIG- URE 4;

FIGURE 6 is a view taken on the line 6-6 of FIG- URE 4;

FIGURE 7 is an isometric view of a modified form of the tamping shoe structure employed with the machine of the present invention;

FIGURE 8 is an isometric view of another modiiied form of the tamping shoe structure;

FIGURE 9 is a schematic view of four units working at various levels in loose soil to be compacted;

FIGURE 10 is an isometric view of a modified form of ythe machine according to the present invention;

FIGURE l1 is a side View in elevation of the assembly of FIGURE 10;

FIGURE 12 is a view on an enlarged scale, taken on the line 12-12 of FIGURE 11;

FIGURE 13 is a top plan view of the assembly of FIGURE 10;

FIGURE 14 is a plan View of a still further modified form of the machine, a portion of one unit being broken away and with the top removed;

FIGURE 15 is a side elevational view partially in section of the assembly of FIGURE 14;

FIGURE 16 is a front elevational view of the assembly of FIGURE 14, with a portion of the interior eX- posed;

' FIGURE 17 is a schematic view showing the vibratory action of the machine of FIGURES 1 to 9, with all the units working in unison;

FIGURE 18 is a schematic view showing the vibratory action of the machine of FIGURES 1 to 9, with the units working in pairs; and

FIGURE 19 is a schematic view showing the vibratory action with the units working individually.

Referring in greater detail to the drawings in which like numerals indicate like parts throughout the several views, and with particular reference to FIGURES 1 to 6, inclusive, the soil compaction machine of the present invention is designated generally by the reference numeral 20 and it includes a frame 22 supported for movement over a ground surface by steerable front wheels 24 and the pairs of Wheels 26 of a prime mover 28 at the rearward end of the machine.

The prime mover 28 has a power takeoff 30 and a transmission 32 interposed between the power takeoff 30 and the engine of the prime mover 28.

Within the frame 22 are a plurality of pairs of soil compacting units 34 arranged in lateral fixed spaced relation and positioned in tandem spaced relation.

Means is provided mounting the units 34 within the frame 22 for movement together from a position spaced above a ground surface to a position in engagement with the ground surface. This mounting means is designated generally by the refeernce numeral 36 and will `be described in detail further on in the description.

As the units 34 are identical, only one needs to be described in detail. Each unit 34 includes a housing 38 and a tamping shoe 40 depending from the housing 38.

Within the housing 3S is a vertical thrust applying mechanism designated generally by the reference numeral 42. The vertical thrust applying mechanism is operatively connected to the housing 38 for imparting up and down impacting movement to the tamping shoe 49 with respect to the ground surface.

With reference to FIGURES 3 to 6, inclusive, the vertical thrust applying mechanism 42 is shown to include a vertically disposed shaft 44driven by a flexible coupling element 46. The shaft 44 is mounted in a bearing 4S in the upper wall of the housing 38 and a pinion 50 is carried on the-lower end of theshaft 44. The pinion-S9 is in meshing engagement with another pinion 52 mounted upon a stub shaft 54 having one endjournaled in the upper wall of the housing 38.A

T he stubY shaft 54 carries on its lower end a bevel gear 56 in mesh witlranotlierv and'larg'erbevel-gear 58. The bevel gear 53 is xedly securedbn a first lrotatable shaft 69 having Vits ends journaled in the side wlls'ofthe housing38.-'

A second rotatable shaft y62 is arranged in parallel spaced relation with respect'to the shaft ,6d-and also has its ends journaledin lthe side walls of vthe housing 38. The shafts 66 and'62` are disposed horizontally and carry means drivingly connectingthe shafts60` and 62Vtogether so that they rotate in opposite directions. .driving means is best showniinFIGURE'fl and it consists in a first spur gear 64 mounted on the shaft 60 in meshing engagement with a sccond'spur gear`66 inountedfon the shaft 62.v Y 4 With reference to FIGURE 6, eccentric Weights 68 are carried by each bf the shafts'60`and62 and afdisc 76 attaches the weights 68 to each ofthe shafts 6.0 and 62'. The weights-68 are disposedn each sideof the spur gear 64 and connected to ,the 'shaft 60 by the one disc 7i) on each* side 4of the spur gear 64, withv the` other weights 68 on each side of the spur gear 66 and coni' necteditothe sha`ft`62y by another disc'70 on each side of the spur gear 66." v

Each weight 63 is conformably shaped to a sector of a circle and is fabricated (from a flat relativelyl thick rsheet of heavy metal. i Asrn'any weights 68 as are desired may be secured to each disc 70, bolts 72 serving as fastenin means for fixing the weights 68 to the disc 70.

Means is provided operatively connected to the units 34 for effecting theV upward and downward movements of the units 34 with respect to the vground surface. Speciically, this means consists-of the mounting means 3:6 on each side of each unit 34 land having its lower end connectedV to the unit`3`4 and'its'uppe'r end connected to theframeZZ. Y fi -V vrThe mounting means 36 of each unit 34 consists in a post '74 rising from each side of the'unit 34 intermediate the ends thereof. A horizontally disposed `pinA 76 extendsV through the upper end of`eacli post 74 and a U-shaped clevis 7E has its 'legs'pivotally' connected to the pin 76. i

A exible cable S connects each clevis 78 to the free end of an actuating arm 82. of a hydraulic cylinder .assembly 84. The cylinder of each assembly 84 is fixedly secured to an adjacentV portion of the machine frame 22.

Conduit means as at 86 in FIGURE 2 connects each hydraulic cylinder assembly 84 to a control valve 83 and a hydraulic fluid pump and reservoir system as at 9i), the pump being driven by the Vengine of the prime mover 28 in a conventional manner.

A driven shaft 92 extends longitudinally of the frame 2.2., as shown in FIGURE 2. One end of the shaft 92 is operatively connected in a gear box 941to a vertical shaft 96 at the upper end of the latter. The lower 'end of the shaft 96 extends into the power takeoff 30 of the prime mover 2g. The driven'shaft 92 extends between the gear boxy 94 and other gear boxes 9d positioned above each of the units 34, the shaft- 92 being in sections but having only a single reference numeral for reasons of simplicity. Y- -Y f ri`he present invention provides individual telescopingly arranged universal joint coupling means operatively connected to a shaft 44of each vertical thrust applying mechanism 42. This means is shown in detail in-FG- URE 3 and it consists in the previously mentionedv flexibie coupling element 46 on the upper endof the shaft 44,

the square shaft 1Q@ having its lower end connected to the element 46 and its upper end slidably within a hollow shaft 102 having a square bore therein. The upper end of the shaft 102 is pivotally connected to another exible coupling or universal joint 1%4 carried o-n the lower end of an output shaft 106 which projects from the adjacent gear box 98A andis operatively connected to the driven shaft 92.'

The speed of rotation of the driven shaft 92 is controlled by a conventional gear shift lever 19S projecting into the transmission 32.

Tow bars 169 extend between each unit 34 and an adjacent part of the frame 22 and have their ends connected for universal movement to the units 3d and the frame 22. There arefour tow bars 109 connecting each unit 34 to the frame ,ft24 against swiveling movement or tilting movement-,L'but'permitting upwardv and downward movement.y l

In FIGURE 7, the numeral 116 refers to the bottom plate'of one 'of the unitsi; A plurality of posts 112 are arranged in two-rows' in staggered relation and carry on their lower ends tamping shoes 4d. The posts 112 are dependingly carried'by the plate 110.

'In FGURE 8, the numeral 114 represents the bottom plate of a unit 34 and the numeral 116 represents a single row'ofposts depending from the plate 114 and carry on their lower-end a single tamping shoe 4G.

With reference to FriGURES'l to13,'incl=usive, a modified'form of the soilcompaction machineof the present invention is shown and designated generally by the reference numeral 118.

In this form of the invention, an overhead frame 120 is supportedat oneend by wheel-s 122 and at the other end by attachment' to a prime mover such as is designated in 'FIGURE 1l by the reference numeral 124.

A pairof tarnping units 34 are arranged in lateral spaced `relation beneath the frame 126 and are connected to the'frame 126` for upward and downward movement into and out of the ground-engaging position. Each unit 34' has a plurality of posts 148 arranged in two rows in longitudinal spaced relation and carry on their lower endsv tamping shoes 159, the posts 148 being dependently carried by the unit. A hydraulic cylinder assembly 126 is mounted on a lower portion of the frame 12@ adjacent each of the rear wheels 122 and is operatively connected to'the adjacent unit 34 by means of a support structure 12S projecting from the adjacent unit 34'. Upon admission of fluid into one end of the hydraulic cylinder assembly 126, the unit 34 is raised with the tow bars 13u serving as a parallelogram structure keeping the adjacent unit 34 level .and against tilting movement when raised by the hydraulic cylinder assembly 126.

As shown most clearly in FGURE 13, each unit 34' is connected by. a pair of tow bars 130 adjacent each side edge'thereof, the tow bars of each pair of tow bars crisscrossing each other and serving to prevent swinging movement of the unit 34 relative to the frame 120.

One end of each tow bar 130 is connected by a universa-l joint to the adjacent part of the unit 34' and the other end is similarly connected to a horizontal beam structure 132, forming a forward and lower portion of the frame 120.

The prime mover 124 has a power takeoff 134 connected by a flexible vand telescoping coupling means, at .136 in FIGURE 11, to the driving means for the vertical thrust applying mechanism within the unit 34. In this form of the invention, the input shaft 138 of the vertical thrust applying mechanism is connected by a exible and telescoping coupling means to a gear box 142 into which extends the other end of the coupling means v136, the coupling means being the same as that shown and described inthe form of FIGURES'I to 6 wherein the input shaft 44 of the oscillating mechanism is connected to the output shaft 106 projecting Vfromthe gear box 9S, and including a flexible conplingmember 139 on the input shaft 13S of the oscillating mechanism within the unit 34', a flexible coupling member 141 on the output shaft 143 in the gear box 142, a square shaft 145 carried by the .coupling member 139 and siidably telescoping into a square bore provided in a hollow shaft 140 carried by the coupling member 141.

Suitable conduit means 144 and control valve means 146 connect each of the hydraulic cylinder assemblies 126 to the hydraulic lluid pressure system of the prime mover 124, in a conventional manner.

Within each unit 34' is the same vertical thrust applying mechanism 42 previously described with reference to the form of the invention shown in FIGURES 1 to 6. In FIGURE 12, dotted lines referenced by the numeral 70 indicate the disc 70 on which are carried the weights 68 of the previously described invention, the weights not being shown in this view. A draw bar 143 on the front of the frame 120` connects the machine 118 to a hitch element 145 on the prime mover 124.

With reference to FIGURES 14 to 16, inclusive, a

further form of the machine of the present invention is shown in which there is no supporting frame but the units 34"'and 34 have tamping shoes in the form of rollers 152 depending therefrom and rotatable about an axle 154 as a horizontal axis.

, In this form of the invention, there are six shafts disposed horizontally above the legs in lateral spaced relation longitudinally of the axis of travel of the units 34 and 34". One such shaft is shown in FIGURE 16 and designated by the numeral 156. The shafts 156 carry weights 158 on one side thereof for rotation therewith.

One of the shafts 156 projects forwardly of the unit 34"" and is connected by a universal joint 160 to a telescoping shaft assembly 162 at one end of the latter. The `other/end of the shaft assembly 162 is connected by another universal joint 164 to one of the shafts 156 of the unit 34", such one shaft of the unit 34" projects rea-rwardly of the unit 34 in axial alignment with the projecting portion of the shaft 156 of the unit 34"', as shown most clearly in FIGURES 14 and 15.

A gear case 166 is carried on the front of the unit 34 and has an input shaft 16S connected by a flexible coupling or universal joint 176 to one end of a telescopic lshaft assembly 172 which has its other end operatively connected to the power takeoff of the towing vehicle, the towing vehicle being represented by a draw bar element 174, shown in dotted lines in FIGURE 14.

A tow bar 176, V-shaped in contiguration, projects rigidly from the front of the unit 34 and has its apex pivotally connected for swinging upward and downward movement of the unit 34" to a hitch element 178 carried by the draw bar 174. Another tow bar 186, also V- shaped in outline, has its apex secured to a hitch element 182 on the back of the unit 34 and is itself xedly secured and projecting forwardly from the unit 34".

In operation, employing the machine 241, as above described with reference to FIGURES 1 to 6, the units 34 are normally held in the elevated positions by the admission of fiuid under pressure into the cylinders of the hydraulic cylinder assemblies 84 of the mounting means 36 to raise the actuating arms S2. This raises all of the units 34 together and in unison and the machine 20 may be transported over roadways or the like to the place of operation.

Upon release of the fluid under pressure in the hydraulic cylinders, gravity will return the units 34 to the position in which the tamping shoes 40 engage the ground surface.

Upon the application of rotative power to the shaft 92 from the power takeoff 30, and at a desired speed as determined by the setting of the transmission 32, the vertical thrust applying mechanism 42 in each unit 34 will be set into operation.

The rotative power is transmitted through the pinions 6 50 and 52, bevel gears 56 and 5S, to the shaft 611 and then by means of the spur gears 64 and 66 to the shaft 62 for rotation of the shaft 6i) in one direction and rotation of the shaft 62 in the other direction. The eccentric connection of the weights 63 to the respective shafts 60 a-nd 62 effects the transmittal of a large amplitude of vertical tamping movement to the housing 38 of each unit 34 and this tamping movement of the housing 3S results in the tamping shoes dit striking the ground repeatedly to effect compacting of the soil on the ground.

With reference to FIGURE 9, the reference character a refers to a dotted line representing a substantially solid ground surface. Over the ground surface is distributed uncompacted soil to a heighth here illustrated as an example substantially equal to the level indicated by a dotted line anddesignated by the reference character 19.

It has been found that as the machine 20 travels in the direction indicated by the arrow in FIGURE 9, the tamping shoes 40 will penetrate to the bottom of the layer of uncompacted soil and start compaction at the bottom of the layer and compact upwardly, thus producing uniformity of density at the bottom of the layer to the top of the layer. This eliminates the undesirable condition of low density in the bottom of the layer of compacted soil which is frequently the result of compacting soil by the use of conventional compacting machines.

It has also been found that by varying the positions of the weights 68 with respect to each other when the machine is at rest, the units 34 may be made to apply thrusts vertically so as to have the. shoes 4t) strike the ground simultaneously, as in FIGURE 17, and represented by a wave form. Alternatively, the weights 68 may be arranged so that the striking movement of the units 34 is such that two units are striking at once while the other two are moving upwardly preparatory for making striking blows to the soil. This is represented in wave form in FIGURE 18. Also, the weights of the units may be adjusted relative to each other So that each unit strikes individually as represented by the wave form of FIG- URE 19.

One of the principles of operation is that as the shafts 60 and 62 rotate, the weights 68 move outwardly from each other for part of the revolution of the shafts 60 and 62 and then move toward each other. This movement cancels out any vibratory movement in a horizontal plane and results in a large amplitude of vertical tamping motion for each unit 34.

The same results are obtained with using the machines shown in FIGURES 10 to 12, or FIGURES 14 to 16, with slight variations in the results.

Using the machine shown in FIGURES 14 to 16, the units 34 and 34"' are not raised between tamping operations but are lrolled over the surface of the soil with no pow-er supplied to the vertical thr-ust applying mechanisms therein.

It is to be understood that the forms of the tamping shoes 4t?, 46 and 46" are such that they may be interchanged for use with particular soils to meet specific problems in compacting such soils.

.A feature of the Iinvention is that by adjusting the frequency with which the shoes contact and strike the earth surface, by varying the relative positions of the weights, Ithis provides a machine producing high frequency vibration-s in the earth by means of a series of low frequency impact tampers, namely, the units 34, 34, 34 and 34"', and their associated tamping shoes or rollers. The net resuit is that the larger mass of the earth is consolidated by high frequency impulses while the localized mass at the surface is being compacted by the sharp penetrating blows of the individual shoes.

It has been found that using the mach-ine of the present invention in each of its forms, a single pass over the soil area to be compacted is all that is necessary to completely compact the soil yfor use as a base for roadways, landing strips, or the like, wherever a compact soil surface is desited. i

.While it is shown in the machine 20, the units 34 are arranged in lateral xed spaced relation and positioned in tandem spaced relation with the units `of the respective -pairs inlinear alignment, in the machine 113 the units 34' are-in lateral xed spaced relation, and in the iinal form of the invention of FIGURES 14 to 16, the units.

34 and 34 are in longitudinalspaced relation, other arrangements are ycontemplated within the scopeof the movement of said units,each1of said-units including housing having a'bottom, a tamping .shoe depending. from the bottom of rsaid housing, and a vertical thrust applying mechanism within saidfhousing andoperatively con` nected tosaid housing for imparting up anddownjrnovement to said shoe `with respect to said ground surface, towbars extending from each of' said units jto `an adjacent part of said frame yand y.being-universally connected atftheir -ends for' permitting movement.. of said: units re# lative to Vsaid frame,lsaid thrust mechanisms havingI an input shaftprojecting yout of the adjacenthousing, .an output shaft on saidframe for each of the input shafts of sai-d thrust mechanisms, Vand an individual telescoping universal'joint-coupling means connecting` each of said input shafts to the adjacent output shafts. y p f 2. The soil compactionmach-ine according to claim 1 wherein said individual telescoping -coupling'means corn-` prises a pair of shafts telescop-ing into eachother and having a universal coupling on. each. 'ofthe free ends thereof connected to adjacent input .and output shafts.

3. The soilcompaction machine according to claim 1 wherein thetamping shoe in each 'unit comprises .a pair of rows of spaced shoes arranged in longitudinally spaced relation below and spaced'fromV the bottomLot the .housing of each unit and extending the fulllwidth` ofsaid bottom. .I Y

4. The soil compaction machine according to claim 1 wherein the vtamping shoe in each? unit' comprises a;.pair of rows of spaced shoes arranged in longitudinally spaced relation below and spaced from the bottom of .thehouse ing of each unit and extending the full width of said bottom, the shoes of one ofsaid rows being staggered with respect to the shoes of the Vother of said rows.

5. ln a soil compaction machine,l a frame supported for movement over a ground surface, a plurality of pairs of soil compacting units arranged in lateral fixed spaced relation positioned in tandem spaced relation within said frame, means mounting said units in said frame for movement together from a position spaced above the ground surface to a position in engagement with said ground surface, hydraulic means operatively connected to said frame for eifecting the movements of said unitsfler.ib le cable means connecting ,each of said units to said hy-y draulic means', each ofsaid units .including a housing having a bottom, a tampingshe depending fromV the bottom of said housing, andavertical thrust appiyingrnechanisin Within said housing and operatively connected to said housingfor .impartingfup and .down movement to said' shoe with respect to said Vground surface, towj bars extending between. each unit andan' adjacent part of said frame and being' universally .connected at their .ends for mechanisms, andan individual telescoping'universalnjoint.

permittingmovement of. said'units relative to said frame,

each of said thrust mechanisms vhaving aninput shaft pro,-

jecting. out of the. adjacent housinggI ,anv output shaft-on said frame foreach of the y.inputfy shaftsof4 saidthrust coupling means conneotingleachioffsaidinput'shafts to theadjacent outputeshaft. 6. ln .a soilncompaotin machine, a Eframesupported for movement over aground surface, a pluralityofrpairsj of soil compactingunits arrangedin" lateral tired spaced relation positioned intandem. spaced relationliwithin said ground surface, hydraulicmeans operatively Vcoririected tov said frame forerfrecting the..rnovements of said units, flexible cable means connecting "each of Vsaid .units'tosa'id hydraulic m eans,ea`ch of said unitsincluding a housingv having' a" bottom, aqtamping shoe depending fromfth'e bottom of said"housing,.and a. vertical thrust applying.

frame,means mounting f said units. in said. frame lfo'r' movement togetherfrom a, position spaced.. above the.

groundsurface to. a .position in vengagei'nent withAk said mechanism Ywithin,saiclhousirig4v and operatively'connected to said housing for imparting up and down movement to.

said shoe with respect toV saidground 4, surface, tow fbars extending between each uni-'tand an; adjacentpart of said frame and being universally connected at their ,ends for permitting movement of said units relative to -said'frame, each of said thrustY mechanisms having an.A input shaft projecting lout `of the .adjacent housing, a driven shaft extending; longitudinally 'of-said frame, `a plurality/.fof output shafts one for each input shaft operatively connected to said driven shaft, andv an`individual`telescoping universal joint coupling means connecting, cachot 4said inputshafts to the adjacent output shafts. v f

References Cited theile of this patent UNITEDSTATES PATENTS 1 

1. IN A SOIL COMPACTION MACHINE, A FRAME SUPPORTED FOR MOVEMENT OVER A GROUND SURFACE, A PLURALITY OF SOIL COMPACTING UNITS ARRANGED IN LATERAL FIXED SPACED RELATION MOUNTED IN SAID FRAME FOR MOVEMENT TOGETHER FROM A POSITION SPACED ABOVE A GROUND SURFACE TO A POSITION IN ENGAGEMENT WITH SAID GROUND SURFACE, MEANS OPERATIVELY CONNECTED TO SAID UNITS AND SAID FRAME FOR EFFECTING THE MOVEMENT OF SAID UNITS, EACH OF SAID UNITS INCLUDING A HOUSING HAVING A BOTTOM, A TAMPING SHOE DEPENDING FROM THE BOTTOM OF SAID HOUSING, AND A VERTICAL THRUST APPLYING MECHANISM WITHIN SAID HOUSING AND OPERATIVELY CONNECTED TO SAID HOUSING FOR IMPARTING UP AND DOWN MOVEMENT TO SAID SHOE WITH RESPECT TO SAID GROUND SURFACE, TOW BARS EXTENDING FROM EACH OF SAID UNITS TO AN ADJACENT PART OF SAID FRAME AND BEING UNIVERSALLY CONNECTED AT THEIR ENDS FOR PERMITTING MOVEMENT OF SAID UNITS RELATIVE TO SAID FRAME, SAID THRUST MECHANISMS HAVING AN INPUT SHAFT PROJECTING OUT OF THE ADJACENT HOUSING, AN OUTPUT SHAFT ON SAID FRAME FOR EACH OF THE INPUT SHAFTS OF SAID THRUST MECHANISMS, AND AN INDIVIDUAL TELESCOPING UNIVERSAL JOINT COUPLING MEANS CONNECTING EACH OF SAID INPUT SHAFTS TO THE ADJACENT OUTPUT SHAFTS. 